Network interface units constitute the demarcation between the customer's equipment and a telecommunications network. In buildings including multiple subscribers, the interface unit is typically mounted in a basement and includes an array of customer bridges, each bridge being coupled to an individual subscriber's line. The bridges are coupled to the network through an RJ11 jack and plug so that the customer can plug a working phone into the jack to determine if any problem lies in the customer or network side of the telecommunications system. Network interface units also typically include a building entrance protector portion which comprises a cable splice chamber and a protector field for providing surge protection for each customer. (For an example of a network interface unit, see U.S. Pat. No. 5,363,440 issued to Daoud).
In the splice chamber, it is usually desirable to provide strain relief for the incoming cable to prevent damage thereto. Standard brackets for holding the cable are effective, but expensive. It is also desirable to provide a grommet at the entry point of the cable in order to prevent the entry of pests or dust into the unit and prevent fire from escaping the splice chamber. A typical grommet comprises a compliant material with a series of perforations in the shape of concentric circles which can be cut out to define an opening according to the size of the cable. (See, U.S. Pat. No. 4,704,499 issued to Faust, and U.S. Pat. No. 4,988,834 issued to Birch.)